Question

The change in entrophy of 2 moles of ideal gas upon isothermal expansion at `243.6 K` from 20 liter until
the pressure becomes 1 atm, is :
A. 1.385 cal/K
B. `-1.2 cal//K`
C. `-30 J//mol.K`
D. None of these

Answer 1

Correct Answer - C
`DeltaS= nRT In (V_(2))/(V_(1))`
`V_(2) = 40`
`V_(1) = 20`
`DeltaS = 2 xx 2 In 2`
` = 4 In 2 = 2.77 cal`